All powers of the city shall be vested in the officers provided for in this charter. Where any existing or future acquired power is not assigned to a specific officer, it shall be deemed to be among the powers of the city council and may be assigned by council to other officers of the city. All powers shall be exercised in the manner prescribed in this charter, or if the manner be not so prescribed, then in the manner prescribed by ordinance. If no procedure is prescribed either by the charter or by ordinance, then that provided by general law shall be followed until the city council shall provide a different procedure by ordinance.